The invention relates generally to a system and method for operating a turbo-charged compression-ignition engine and, more specifically, to a system and method for reducing specific fuel consumption and engine exhaust emission in a turbo-charged diesel engine in a locomotive.
In a compression-ignition engine, such as a diesel engine, a fuel injection system injects fuel (e.g. diesel fuel) into compressed air within each of the engine cylinders to create an air-fuel mixture that ignites due to the heat and pressure of compression. Unfortunately, engine efficiency, power output, fuel consumption, exhaust emissions, and other operational characteristics are less than ideal. In addition, conventional techniques to improve one operational characteristic often worsen one or more other operational characteristic. For example, attempts to decrease specific fuel consumption often cause increases in various exhaust emissions. Vehicle exhaust emissions include pollutants such as carbon monoxide, nitrogen oxides (NOx), particulate matter (PM), and smoke generated due to incomplete combustion of fuel within the combustion chamber. The amount of these pollutants varies depending on the fuel-air mixture, compression ratio, injection timing, ambient conditions, and so forth.
Therefore, a technique is needed for reducing specific fuel consumption without increasing certain exhaust emissions, such as NOx, in a turbo-charged diesel engine.